Class 10 Science Chapter 2 MCQ

Chloralkali is a process used in industries to produce chlorine and sodium hydroxide (caustic soda). This happens by the electrolysis of NaCl (commonly known as brine).

Most of the plants grow best when the pH of the soil is close to 7. If the soil is too acidic or too basic (too alkaline), the plants grow badly or do not grow at all. The soil may be acidic or basic naturally. The soil pH is also affected by the use of chemical fertilizers in the fields. The pH of acidic soil can reach as low as 4 and that of the basic soil can go up to 8.3. Chemicals can be added to soil to adjust its pH and make it suitable for growing plants.

HCl is a strong acid. When HCl is mixed with water, its molecules dissociate completely to furnish H+ ions and Cl– ions. This H+ ion combines with water molecules to produce hydronium ions.

Our stomach produces hydrochloric acid (of pH about 1.4). This dilute hydrochloric acid helps in digesting our food without harming the stomach. Sometimes, excess of acid is produced in the stomach due to various reasons. The excess acid in the stomach causes indigestion which produces pain and irritation.

If a solution turns universal indicator green, then it will be a neutral solution (which is neither acidic nor basic). Thus, water will produce a green colour with universal indicator.

Citric acid is not a mineral acid. It is an organic acid or edible acid that is derived from organic compounds. Note: Mineral acids or inorganic acids are generally prepared from inorganic compounds such as minerals present in the earth’s crust. For examples, HCl (hydrochloride acid), H2SO4 (sulphuric acid) and HNO3 (nitric acid) are mineral acids. These acids dissolve in water to produce H+ ions.

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are incorrect except one. Hence, your answer will be option [D]. Sulphuric acid (H2SO4) and nitric acid (HNO3) are also strong acids. Carbonic acid (H2CO3) and sulphurous acid (H2SO3) are also weak acids. Strong acids also have a high electrical conductivity.

Lime (CaO) is the base that reacts with a dilute acid such as HCl to form a salt called “Calcium Chloride”. It is an exothermic reaction and releases water but no carbon dioxide. Mable or limestone (CaCO3) or baking soda (NaHCO3) react with HCl to release CO2.

The hydrogen containing compounds like glucose and alcohol do not produce hydrogen ions or some other ions in solution. So, due to the absence of ions, glucose solution and alcohol solution do not conduct electricity.

All the acid solutions conduct electricity. Here, all the statements are correct except one. Hence, your answer will be option [D].

Generally, acids are stored in containers made of glass and ceramics because they are not attacked by acids. Acids are never stored in metal containers because they gradually corrode and eat up the metal container.

When the pH of an aqueous solution is higher, acidic properties are weak. Thus it is a base. When the pH an aqueous solution is lower, basic properties are weak. Thus it is an acid. Note: In 1909 Sorenson devised a scale (known as pH scale) on which the strength of acid solutions as well as basic solutions could be represented by making use of the hydrogen ion concentrations in them. A pH scale is used to measure the acidic and basic strength of an aqueous solution. This scale is marked from 0 to 14. A solution is neutral if its pH value is 7. An acidic solution has a pH less than 7. This means an acidic solution has more concentration of H+ ions. A basic solution has a pH more than 7. This means a basic solution has more concentration of OH– ions.

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

When carbon dioxide gas is passed through lime water, the lime water turns milky due to the formation of a white precipitate of calcium carbonate: You can easily understand by this equation: Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s) + H2O (l) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water

Common salt (NaCl) is formed by reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH). It serves as an important raw material for the production of various chemical compounds such as caustic soda (sodium hydroxide), washing soda (sodium carbonate), baking soda (sodium bicarbonate) used in various industries. Chlorine gas obtained is used for making bleaching powder (calcium hypochlorite).

Water is added to concentrated acid to dilute it, then a large amount of heat is evolved at once. This heat changes some of the water to steam explosively which can splash the acid on our face or clothes and cause acid burns. Note: When a concentrated acid is added to water for preparing a dilute acid, then the heat is evolved gradually, and easily absorbed by the large amount of water

The acids prepared from the minerals of the earth are called mineral acids. Mineral acids are manmade acids. The three most common mineral acids are: Hydrochloric acid, Sulphuric acid and Nitric acid. Concentrated mineral acids are very dangerous. They can burn our hands and clothes. These acids should be handled with care.

Firstly, we have to understand that a strong base cannot be used to neutralise the acid as it can corrode the skin. Wash the hand immediately with plenty of water as it helps to wash away most of the acid. Thereafter apply a paste of baking soda (NaHCO3) to neutralise the little acid if any, left over the hand. Baking soda has weak basic properties that is used to neutralise the acid.

Here, all the statements are correct. Hence, your answer will be option [D].

Calcium phosphate Ca3(PO4)2 is basic salt, as it is formed by the combination of a weak acid (phosphoric acid) and slightly stronger base (calcium hydroxide). Bacteria feed on sugars commonly found in foods and produce acids in the mouth decreasing the pH level to 5.5 or lower. Thus, eroding the enamel that is basic in nature.

Sodium carbonate (Na2CO3) is the salt formed by the combination of a weak acid such as carbonic acid (H2CO3) and a strong base such as sodium hydroxide (NaOH). You can easily understand by this equation: 2NaOH + H2CO3 → Na2CO3 +2H2O Note: The salt formed by the combination of weak acid and a strong base is basic in nature. Basic salts have pH more than 7.

The aqueous solution is a base as it turns red litmus solution blue. An acidic solution such as hydrochloric acid (HCl) would reverse the change. In contrast, hydrochloric acid would turn blue litmus solution to red.

Baking soda does not contain water of crystallization. The chemical formula of baking soda is NaHCO3. Its formula does not show any association with water molecules. Other three contain water of crystallization blue vitriol (CuSO4.5H2O), washing soda (Na2CO3.10H2O) and gypsum (CaSO4.2H2O).